Metal net for treatment of gases

ABSTRACT

The invention relates to a metal net for use in gas treatment and an gas treatment equipment including this metal net and a method for cleaning exhaust gases of engines. The invention also relates to equipment for manufacturing such a metal net. The equipment according to the invention is particularly suitable as a catalyzer for small engines. A metal net comprises frame components fastened to each other at least at some points with weld joints made with a pulsation arc technique

TECHNICAL BACKGROUND

The invention relates to a metal net for use in gas treatment and a treatment equipment including this metal net and a method for cleaning exhaust gases of engines. The invention also relates to equipment for manufacturing such a metal net. The equipment according to the invention is particularly suitable as a catalyzer for small engines.

Several types of frame constructions are used in the treatment of exhaust gases. One commonly used frame solution is a net-like construction, which includes metal wires. However, the problem with this type of net-like frame is its poor mechanical resistance particularly in demanding burning conditions.

GENERAL DESCRIPTION OF INVENTION

A treatment cell for exhaust gases has now been invented, which is particularly resistant even in demanding conditions.

To achieve this object, the invention is characterized by the features specified in the independent claims. Some of the advantageous embodiments of the invention are set forth in the other claims.

In the treatment cell for exhaust gases according to the invention, frame components of the metal net are fastened to each other at least at some points with weld joints produced with a pulsation arc technique. This pulsation arc weld joint essentially strengthens the net-like frame. Advantageously the metal net has pulsation arc weld joints essentially at all connection points of the frame components. To mention as a reference value, without pulsation arc weld joints the resistance of the net-like treatment cell was only about 50 h in the reference test, whereas the resistance of the cell including weld joints made with the pulsation arc technique was 125 h.

The metal net according to the invention is extremely resistant, because the joints prevent the frame components from vibrating relative to each other and individually. This is particularly advantageous for example when the frame components are covered with a support material. Fastening of the frame components advances, for example, secure attachment of the support material layers, which can sometimes be quite thick, connected to the intersections. This improves the resistance of the coated frame material.

According to one embodiment of the invention, the thickness of the metal net frame component is 0.15 mm or more, such as advantageously 0.3-0.6 mm. In principle, a treatment cell according to the invention can also be manufactured from frame components having a very high thickness. The frame component can advantageously be less than 2.0 mm. In this case it is sufficiently thin to allow forming the metal net advantageously to the desired shape. The treatment cell can be made mechanically extremely resistant, which further improves its usability.

According to one embodiment of the invention, the material of the frame components of the metal net is advantageously stainless steel, such as W1.4767, W1.4725 or W1.4301. This material is resistant, which allows making the product maximally resistant even for demanding conditions.

The size of the metal net according to the invention can vary freely. The thickness of the metal net can be e.g. 1-50 mm, such as advantageously 5-15 mm. In relation to the volume, it is then maximally resistant for the construction, and also technically advantageous to manufacture.

According to one embodiment of the invention, the treatment cell is essentially covered with catalyzing materials. This type of cell can be efficiently used particularly as a catalyzer for small engines. Such small engines include e.g. chain saws, grass trimmers, mopeds, scooters, motorcycles, outboard motors and aggregates.

A treatment cell according to the invention can also be used for exhaustion of smoke and volatile gases. Applications can also include hoods and filters, for example.

DETAILED DESCRIPTION OF INVENTION

Some of the embodiments of the invention are described below in detail by making reference to the enclosed drawing.

FIG. 1 is a cross-sectional view of a treatment cell for exhaust gases welded with a pulsation arc welding technique.

In FIG. 1 the frame components 2 of the metal net of the treatment cell 1 for exhaust gases are fastened to each other with pulsation arc weld joints 3. The metal net 1 forms a resistant construction, as the frame components 2 are connected in all directions to each other with weld joints 3. 

1. A metal net for use in gas treatment, wherein frame components of the metal net are fastened to each other at least at some points with weld joints made with a pulsation arc technique.
 2. A metal net according to claim 1, wherein the thickness of the frame component is 0.15 mm or more.
 3. A metal net according to claim 1, wherein the material of the frame component is stainless steel, such as W1.4767, W1.4725 or W1.4301.
 4. A metal net according to claim 1, wherein the metal net is essentially covered with catalyzing materials.
 5. Equipment for manufacturing a metal net frame for use in gas treatment, wherein the equipment of the treatment cell comprises means for fastening the metal net (1) and a pulsation arc welding machine for connecting the metal wire frame components to each other with pulsation arc weld joints (3).
 6. Gas treatment equipment, comprising one or more metal nets (1) having frame components of the metal net fastened to each other at least at some points with weld joints made with a pulsation arc technique.
 7. A method for cleaning exhaust gas of engines, wherein exhaust gas is cleaned with a metal net having frame components fastened to each other at least at some points with weld joints made with a pulsation arc technique.
 8. A method according to claim 7, wherein said engine is a small engine. 